Ultraselective and ultrasensitive detection of H2S in highly humid atmosphere using CuO-loaded SnO2 hollow spheres for real-time diagnosis of halitosis

Abstract The CuO-loaded SnO 2 hollow spheres were prepared by ultrasonic spray pyrolysis and their H 2 S sensing characteristics in dry and humid atmospheres for the diagnosis of halitosis were investigated. The loading of CuO to SnO 2 hollow spheres decreased the humidity dependence of H 2 S sensing characteristics down to negligible level, increased the gas response (ratio of resistance to air and gas) in highly humid atmosphere (relative humidity 80%) to 1 ppm H 2 S from 3.13 to 22.4, and enhanced the selectivity to H 2 S over CO, NH 3 , CH 3 COCH 3 , C 6 H 6 , CH 3 C 6 H 5 , (CH 3 ) 2 C 6 H 4 , and NO at 300 °C. Ultraselective and ultrasensitive detection of H 2 S under highly humid atmosphere with negligible interferences from other biomarker gases provides a promising and reliable analysis tool for real-time diagnosis of halitosis from exhaled breath.